This does one last check to see if the file downloaded by
download_from_google_storage.py actually matches its sha1

BUG=

Review URL: https://codereview.chromium.org/1252313005

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@296155 0039d316-1c4b-4281-b951-d872f2087c98